1. Field of the Art
This invention relates to a magnet coupling type rodless cylinder.
2. Prior Art
Magnet coupling type rodless cylinders, which have been known in the art, are generally constituted by a cylinder tube formed of a non-magnetic material in a cylindrical shape, a pair of end covers closing the opposite axial ends of the cylinder tube, a piston received in the cylinder tube for hermetical sliding movements therein, a carriage member axially movably mounted on the cylinder tube to transfer an article along the outer periphery of the cylinder tube, and a magnet coupling provided between and coupling the cylinder tube and the carriage member with each other in such a way that the carriage member is moved in synchronism with the piston when the piston is moved axially within the cylinder tube by introduction of a compressed air pressure through an air charging and discharging port in either one of the end covers of the cylinder tube.
In a rodless cylinder of this sort, the carriage member is usually associated with a rotation blocking mechanism thereby to block rotational movements of the carriage member which would otherwise tend to turn about the cylinder tube. For instance, in case of Japanese Laid-Open Utility Model Application 62-19508 (Utility Model Publication H4-19214), rotational movements of a carriage member are blocked by a plural number of skewer type rods which are extended between end covers at the opposite axial ends of a cylinder tube through a carriage member.
However, conventional rotation blocking mechanisms which have a plural number of skewer type rods passed through a carriage member in such a manner invariably necessitate to increase the diameters of the carriage member and end covers for attachment thereto of the blocking skewer rods, resulting in a substantial increase in size of the rodless cylinder as a whole.
Therefore, there has been a demand for a rodless cylinder with a rotation blocking mechanism which is smaller in size and compact in construction as compared with the above-described conventional skewer rod type blocking mechanism.
In addition, for the purpose of detecting the operating position of a carriage member, in many cases rodless cylinders of this sort are provided with a position detection mechanism, which generally includes a rail member extended between the two end covers, a magneto-sensitive position detector switch mounted on the rail, and a magnet fixed on the carriage member.
For providing such a position detection mechanism on a conventional rodless cylinder, however, it becomes necessary to mount the rail member on the cylinder tube in addition to the afore-mentioned skewer type rods of the rotation blocking mechanism, resulting in a rodless cylinder which is further enlarged in size and complicated in construction involving an increased number of component parts.
These problems could be solved if one succeeds to provide a rotation blocking mechanism which is also capable of supporting a position detector switch in place of the rail member as used on the above-described prior art rodless cylinder. In such a case, measures should be taken to prevent malfunctioning of the position detector switch as caused under the influence of magnetic leakage from the magnet coupling. Besides, if arrangements are made to charge and discharge compressed air into and out of a pressure chamber on one side of the piston via the rotation blocking mechanism, it would become possible to make connections of all piping tubes to the rodless cylinder collectively through one of the end plates in an extremely convenient fashion.